This invention relates generally to the medical field and, more particularly, to the use of photodynamic therapy to treat prostatic tissues, and to the use of transurethral photodynamic therapy to treat malignant transformation of the prostate tissue, such as obstructive carcinoma of the prostate and inflammatory conditions of the prostate. The present invention involves treatment of a patient with prostatic disorders using a photosensitive composition which accumulates in the prostatic tissue.
Various types of prostatic tissue become hypertrophied or increased in size, which increase does not necessarily involve malignant transformation. While the causes of such hypertrophy of the tissue are numerous, until the present invention, the treatments of such hypertrophied tissue have various limitations. In particular, benign prostatic hypertrophy (BPH) causes enlargement of the prostate gland and/or constriction of the urethra. Benign prostatic hypertrophy is a relatively common disorder in older males. Another type of prostate disorder is cancer of the prostate, such as obstructive carcinoma of the prostate. Still another type of prostate disorder is prostatitis. Prostatitis is an inflammatory condition due to an infective pathogen, such as a bacterium or other microbe. Often prostatitis does not respond well to antibiotic treatment. In chronic or severe cases of prostatitis, abscesses can form and destroy prostatic tissue. Some manifestations of these prostate disorders cause a constriction of the urethra within the prostate and results in various symptoms including stanguria, nocturia, frequency of urination and sometimes retention of urine.
Currently there are various methods for treating prostatic disorders including surgical treatment, drug therapy, hypothermia and hyperthermia treatment, implantation of prostatic stents and enlargement of the urethra using dilation balloons.
The surgical treatment of these disorders involves exposing the prostate and removing the affected prostatic tissue under direct vision by the surgeon. Another surgical method involves transurethral resection wherein an instrument is placed in the external opening of the urethra and sections of the prostate gland are removed from within the prostatic urethra. Despite the significant advances in patient treatment using transurethral resection, there is a need for less invasive treatment to relieve the patient of the symptoms of such prostate disorders. It is widely known that complications including bleeding, infection, residual urethral obstruction or stricture, retrograde ejaculation, incontinence or impotence may result from these surgical methods.
One partially effective method in achieving urinary outflow involves the placement of a tube or catheter through the external urethra into the bladder in order to allow urine to flow from the bladder. The urinary catheter may have a balloon at the distal tip which, when inflated within the bladder, prevents the removal of the catheter from the body. This method generally is not a suitable long term treatment since problems from infection and maintenance of the catheter may arise.
Other attempts to treat prostatic disorders involve dilation of the urethra in an area adjacent the prostate gland. Various methods of dilation have been proposed in order to enlarge the urethra to allow for normal urination. One continuing concern is that the prostate gland returns to its original dimensions after dilation. Thus, the dilation provides only a temporary solution to the urethral constriction. The fibrous prostate gland is resilient and causes constriction of the urethra to recur shortly after treatment. This is of particular concern since prostatic disorders involve the fibrous and enlarged tissue of the prostate gland itself. Enlargement by dilation of the urethra wall typically has no lasting effect on relieving the constriction on the urethra since the prostate gland returns to its previous shape shortly after dilation.
Therefore, it is important that a method for treating prostatic disorders include a way to keep the urethra from being constricted by the prostate gland after such treatment. Without such treatment, the patient may be required to undergo repeated treatments in order to maintain the integrity of the urethra lumen.
In photodynamic therapy photosensitive compositions are used to selectively destroy pathologic tissue. For example, various photosensitive compounds localize in tumorous tissue where the compositions absorb light at certain wavelengths when irradiated. The photosensitive compositions are useful due to their ability to localize in the cancerous or tumorous tissue and not in the surrounding non-canoerous or normal tissues.
Photosensitive compositions have been proposed as useful compounds for topical application for diagnosis and treatment of skin diseases. In addition, photosensitive compositions have been proposed for use to sterilize biological samples containing infectious agents such as bacteria and viruses. The bactericidal effects are induced by irradiation of tissues treated with photosensitive compositions against gram-positive and gram-negative microorganisms (Martinetto et al. Drugs Exp. Clin. Res. XII (4) 335-342, 1986). The photosensitive compositions have also been used to decontaminate blood and blood components. In addition, photosensitive compositions have been used in the treatment of blood vessel occlusions such as atherosclerotic plaques, thrombi, and the like.
Photodynamic therapy in combination with hyperthermia has also been proposed as a useful method in treating many of these applications. Photosensitive compositions have also been proposed as useful in the diagnosis of disease. These photosensitive compositions have fluorescent properties and since the photosensitive compositions sequester in diseased tissue, fluorescent measurement can be used to diagnose and localize the disease, or direct therapy.
Until the present invention there has been no suggestion of using photodynamic therapy, either alone or in combination with hyperthermic therapy, in the diagnosis and treatment of noncancerous, prostatic disorders, such as benign prostatic hypertrophy and prostatitis.
Further, until the present invention, there has been no suggestion of using photodynamic therapy in the in vivo treatment of an infectious prostatitis.